Future soil organic carbon stocks in China under climate change

Quantifying soil organic carbon (SOC) is crucial for China's carbon neutrality goals, yet uncertainties exist due to future climate change. We compiled a comprehensive SOC database for China circa 2010 and utilized digital soil mapping methods to estimate SOC. Using a climate data-driven model, we projected SOC changes from 2021 to 2100 under different shared socioeconomic pathways (SSPs). The top 100 cm SOC is predicted to store 81.99 ± 1.90 to 88.92 ± 1.24 Pg C, with 37.8% to 41.7% in the top 20 cm. Under the SSP119 scenario, the top 100 cm SOC would increase by 11.5 ± 5.3 Tg C year⁻¹, contributing to 2.7% ± 1.6% of the carbon sink in China's terrestrial ecosystems over the same period. However, the top 100 cm SOC would transition into a carbon source under SSP245 and SSP585, despite geographical and provincial differences. Maps reveal SOC loss hotspots under SSP245 and SSP585, indicating priority regions for soil carbon conservation efforts.